Thin film forming method

ABSTRACT

A thin film forming method includes: a first operation of supplying a source gas at a first flow rate into a reactor; a second operation of purging the source gas in the reactor to an exhaust unit; a third operation of supplying a reactive gas at a second flow rate into the reactor; a fourth operation of supplying plasma into the reactor; and a fifth operation of purging the reactive gas in the reactor to the exhaust unit, wherein, during the second to fifth operations, the source gas is bypassed to the exhaust unit, and a flow rate of the source gas bypassed to the exhaust unit is less than the first flow rate. According to the thin film forming method, the consumption of the source gas and the reactive gas may be reduced, and the generation of reaction by-products in the exhaust unit may be minimized.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/668,685, filed on May 8, 2018, in the United States Patent andTrademark Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND 1. Field

One or more embodiments relate to a thin film forming method and asubstrate processing apparatus, and particularly, to a thin film formingmethod and a substrate processing apparatus, which are capable ofreducing the consumption of a source gas and a reactive gas used duringa thin film forming process. More particularly, one or more embodimentsrelate to a method of reducing the consumption of a dichlorosilane (DCS;SiH₂Cl₂) source in a SiN thin film deposition process using the DCSsource.

One or more embodiments also relate to a thin film forming method and asubstrate processing apparatus that are capable of preventing thegeneration of reaction byproducts.

2. Description of the Related Art

Semiconductor substrate processing processes, such as a deposition oretching process, have become more complicated as semiconductortechnology has advanced, and thus various types of chemicals areincreasingly being used as raw materials. Accordingly, substrateprocessing equipment having various structures for processing these rawmaterials has been developed.

When heterologous chemicals with high reactivity are used, equipmentoperation may be disrupted by reaction byproducts. For example, reactionbyproducts may remain in an exhaust line as solids, and these residualsolids may reduce exhaust efficiency and cause malfunctions of internalcomponents such as valves, pressure gauges, and the like. In addition,solids remain in a scrubber or exhaust pump, which collects harmfulchemicals before being exhausted to the air, and thus, when overalloperation of a substrate processing apparatus is stopped, it may causebig problems in apparatus operation and productivity improvement.

In addition, to minimize a pressure fluctuation in a reactor during asubstrate processing process, gas pressure in a gas supply line is keptconstant. To this end, in operations other than a source gas supplyoperation to the reactor, a source gas is exhausted via a bypass line atthe same flow rate as the amount of source gas supplied in the sourcegas supply operation. When this method is used, however, a much greateramount of source gas than needed in reaction may be wasted, and a muchlarger amount of reaction byproducts may be produced in an exhaust line,thus adversely affecting the performance of an exhaust line, an exhaustpump, and a scrubber.

SUMMARY

One or more embodiments include a thin film forming method and asubstrate processing apparatus that are capable of addressing theaforementioned problems by reducing the amounts of a source gas andreactive gas bypassed.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments.

According to one or more embodiments, a thin film forming methodincludes a first operation of supplying a source gas at a first flowrate into a reactor via a first mass flow controller; a second operationof purging the source gas in the reactor to an exhaust unit; a thirdoperation of supplying a reactive gas at a second flow rate into thereactor via a second mass flow controller; a fourth operation ofsupplying plasma into the reactor; and a fifth operation of purging thereactive gas in the reactor to the exhaust unit, wherein, during thesecond to fifth operations, the source gas may be bypassed to theexhaust unit via the first mass flow controller, and a flow rate of thesource gas bypassed to the exhaust unit may be less than the first flowrate.

According to one embodiment, a path through which the bypassed sourcegas is discharged may be the same as a path through which the purgedsource gas or reactive gas is discharged from the reactor.

According to one embodiment, the first flow rate, a third flow rate, andrespective processing time periods of the first to fifth operations maybe input to the first mass flow controller, the third flow rate beingless than the first flow rate, and the first mass flow controller may beprogrammed to adjust an amount of the source gas based on the inputfirst flow rate, the input third flow rate, and the input respectiveprocessing time periods of the first to fifth operations.

According to one embodiment, the first mass flow controller may beprogrammed to supply the source gas at the first flow rate during thefirst operation and supply the source gas at the third flow rate duringthe second to fifth operations. A flow rate of the source gas bypassedto the exhaust unit during the second operation may be gradually reducedfrom the first flow rate to the third flow rate, and the flow rate ofthe source gas bypassed to the exhaust unit during the fifth operationmay be gradually increased from the third flow rate to the first flowrate.

According to one embodiment, the third flow rate may be greater than 0and less than the first flow rate. The third flow rate may be about ⅛ toabout 1/10 of the first flow rate.

According to other embodiments, the first mass flow controller may beprogrammed to supply the source gas at the first flow rate during thefirst operation, supply the source gas at the third flow rate after thefirst operation, and supply the source gas at the first flow rate duringa first predetermined period before the first operation.

According to one embodiment, the first predetermined period may beshorter than the processing time of the fifth operation.

According to other embodiments, a total processing time of the second tofifth operations may be 1.5 seconds, and the first predetermined periodmay be 1.3 seconds or less.

According to one embodiment, a length of the first predetermined periodmay not affect a thin film deposited in the reactor. The length of thefirst predetermined period may not affect a thickness and uniformity ofthe thin film deposited in the reactor.

According to one embodiment, the first mass flow controller maycontinuously transfer the source gas during the first to fifthoperations.

According to one embodiment, the reactive gas may be bypassed to theexhaust unit via the second mass flow controller during the firstoperation, the second operation, and the fifth operation, the secondflow rate, a fourth flow rate, and respective processing time periods ofthe first to fifth operations may be input to the second mass flowcontroller, the fourth flow rate being less than the second flow rate,and the second mass flow controller may be programmed to, based on theinput second flow rate, the input fourth flow rate, and the inputrespective processing time periods of the first to fifth operations:supply the reactive gas at the second flow rate during the third andfourth operations; and supply the reactive gas at the fourth flow rateduring the first, second, and fifth operations.

According to one embodiment, a path through which the bypassed sourcegas or reactive gas is discharged may be the same as a path throughwhich the purged source gas or reactive gas is discharged from thereactor, and as the fourth flow rate decreases, amounts of the sourcegas and the reactive gas reacted in the discharge path during the secondoperation may be reduced, and as the third flow rate decreases, theamounts of the source gas and the reactive gas reacted in the dischargepath during the fifth operation may be reduced.

According to one embodiment, the reactive gas may be bypassed to theexhaust unit via the second mass flow controller during the first,second, and fifth operations, the second mass flow controller may beprogrammed to supply the reactive gas at a second flow rate during thethird and fourth operations, supply the reactive gas at a fourth flowrate after the fourth operation, the fourth flow rate being less thanthe second flow rate, and supply the reactive gas at the second flowrate during a second predetermined period before the third operation,and the second predetermined period may be started after the flow rateof the source gas bypassed to the exhaust unit during the secondoperation is reduced to the third flow rate.

According to one or more embodiments, a substrate processing apparatusfor performing a thin film forming process includes: a gas supply unit;a reactor; an exhaust unit including a single exhaust line and connectedto the reactor via the single exhaust line; and an exhaust pump unitconnected to the exhaust unit via the single exhaust line, wherein thegas supply unit includes: a first gas supply pipe through which a sourcegas is supplied from the gas supply unit to the reactor; a second gassupply pipe through which a reactive gas is supplied from the gas supplyunit to the reactor; a first bypass pipe branched off from the first gassupply pipe and connected to the exhaust unit; and a second bypass pipebranched off from the second gas supply pipe and connected to theexhaust unit, wherein, when one of the source gas and the reactive gasis supplied to the reactor via the first gas supply pipe or the secondgas supply pipe, the gas supply unit may be configured to bypass theother gas to the exhaust unit via the first bypass pipe or the secondbypass pipe, and when one of the source gas and the reactive gas ispurged from the reactor to the exhaust unit, the gas supply unit may beconfigured to bypass the source gas and the reactive gas via the firstbypass pipe and the second bypass pipe, respectively.

According to one embodiment, the gas supply unit may further include atleast one mass flow controller, and the at least one mass flowcontroller may be programmed to reduce a flow rate of the correspondinggas when the source gas or the reactive gas is bypassed to the exhaustunit.

According to one or more embodiments, there is provided a substrateprocessing apparatus for performing a thin film forming process, whereinthe thin film forming process includes: a first operation of supplying asource gas; a second operation of purging the source gas; a thirdoperation of supplying a reactive gas; a fourth operation of applyingplasma; and a fifth operation of purging the reactive gas, and thesubstrate processing apparatus includes: a gas supply unit; a reactor;an exhaust unit including a single exhaust line and connected to thereactor via the single exhaust line; and an exhaust pump unit connectedto the exhaust unit via the single exhaust line, wherein the gas supplyunit includes: a first gas supply pipe through which a source gas issupplied from the gas supply unit to the reactor; a second gas supplypipe through which a reactive gas is supplied from the gas supply unitto the reactor; a first bypass pipe branched off from the first gassupply pipe and connected to the exhaust unit; and a second bypass pipebranched off from the second gas supply pipe and connected to theexhaust unit, and the gas supply unit is configured to: supply thesource gas to the reactor via the first gas supply pipe during the firstoperation; supply the source gas to the exhaust unit via the firstbypass pipe during the second to fifth operations; supply the reactivegas to the reactor via the second gas supply pipe during the third andfourth operations; and supply the reactive gas to the exhaust unit viathe second bypass pipe during the first, second, and fifth operations.

According to one embodiment, the gas supply unit may further include afirst mass flow controller and a second mass flow controller. The firstmass flow controller may be configured to control a flow rate of a gasin the first gas supply pipe and the first bypass pipe such that theflow rate in the first bypass pipe is less than the flow rate in thefirst gas supply pipe, and the second mass flow controller may beconfigured to control a flow rate of a gas in the second gas supply pipeand the second bypass pipe such that the flow rate in the second bypasspipe is less than the flow rate in the second gas supply pipe.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects will become apparent and more readilyappreciated from the following description of the embodiments, taken inconjunction with the accompanying drawings in which:

FIG. 1 is a schematic diagram illustrating a substrate processingapparatus according to embodiments of the present disclosure;

FIG. 2 is a schematic diagram illustrating a thin film forming methodaccording to embodiments of the present disclosure;

FIGS. 3A to 3D are schematic diagrams illustrating the substrateprocessing apparatus of FIG. 1 performing the thin film forming methodof FIG. 2;

FIG. 4 is a schematic diagram illustrating a thin film forming methodaccording to other embodiments of the present disclosure;

FIG. 5 is a schematic diagram illustrating a thin film forming methodaccording to other embodiments of the present disclosure;

FIG. 6 is a schematic diagram illustrating a thin film forming methodaccording to other embodiments of the present disclosure;

FIGS. 7A to 7D are schematic diagrams illustrating the substrateprocessing apparatus of FIG. 1 performing the thin film forming methodof FIG. 4;

FIG. 8 illustrates the consumption of a DCS source used via a bypasstube according to DCS-pre-flow time when the thin film forming method ofFIG. 4 is used; and

FIG. 9 illustrates uniformity of a SiN thin film according to DCSpre-flow time when the thin film forming method of FIG. 4 is used.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects of the present description.

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings.

Embodiments of the present disclosure are provided to more fully explainthe present disclosure to those of ordinary skill in the art, andembodiments set forth herein may be changed in many different forms andare not intended to limit the scope of the present disclosure. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the present disclosureto those of ordinary skill in the art.

The terms used in the present specification are merely used to describeexample embodiments and are not intended to limit the presentdisclosure. An expression in the singular encompasses an expression inthe plural, unless context clearly indicates otherwise. In addition,terms such as “comprise” and/or “comprising” are intended to indicatethe existence of stated shapes, numbers, steps, operations, members,elements, and/or combinations thereof, and are not intended to precludethe possibility that one or more other shapes, numbers, operations,members, elements, and/or combinations thereof. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

In the present specification, it will be obvious that, although theterms first, second, and the like are used herein to describe variousmembers, regions, and/or portions, these members, components, regions,layers, and/or portions should not be limited by these terms. Theseterms do not indicate particular order, positional relationship, orrating and are used only to distinguish one member, region, or portionfrom another member, region, or portion. Thus, a first member, region,or portion, which will be described below, may be denoted as a secondmember, region, or portion without departing from the teachings of thepresent disclosure.

Hereinafter, embodiments of the present disclosure will be describedwith reference to the accompanying drawings, which schematicallyillustrate example embodiments of the present disclosure. In thedrawings, variations from the shapes of the illustrations as a result,for example, of manufacturing techniques and/or tolerances, are to beexpected. Thus, embodiments of the present disclosure should not beconstrued as limited to the particular shapes of regions illustratedherein but are to include changes in shapes that result, for example,from manufacturing.

A substrate processing apparatus described herein may be, for example, adeposition apparatus for a semiconductor or display substrate, but thepresent disclosure is not limited thereto. The substrate processingapparatus may be any apparatus needed for performing deposition of amaterial for forming a thin film and may refer to an apparatus in whicha raw material for etching or polishing a material is uniformlysupplied. Hereinafter, a semiconductor deposition apparatus will bemainly described as the substrate processing apparatus for convenienceof explanation.

FIG. 1 is a schematic diagram illustrating a substrate processingapparatus 100 according to embodiments of the present disclosure.

For example, the substrate processing apparatus 100 of FIG. 1 may be anatomic layer deposition apparatus for forming silicon nitride (SiN). Inthe present embodiment, dichlorosilane (DCS; SiH₂Cl₂) is used as asource gas, ammonia (NH₃) is used as a reactive gas, and Ar is used as apurge gas, but the present disclosure is not limited thereto. In thepresent embodiment, the substrate processing apparatus 100 alternatelysupplies a DCS source and ammonia (NH₃) and activates the ammonia (NH₃)with plasma, thereby forming a SiN film, by using a plasma-enhancedatomic layer deposition (PEALD) method.

The DCS source is a gaseous source. The DCS source is directly suppliedto a reactor from a DCS container (e.g., a source gas supply unit 16,which will be described below) installed outside the substrateprocessing apparatus 100, unlike a general liquid source supplied from asource vessel to a reactor by a bubbling method.

Referring to FIG. 1, the substrate processing apparatus 100 may includea gas supply unit, a reactor 10, an exhaust unit, and an exhaust pumpunit 15. The substrate processing apparatus 100 may be implemented insuch a manner that gas is vertically supplied to a substrate using a gasinjection member.

The gas supply unit may include a first gas supply pipe configured tosupply a source gas from the gas supply unit to a reactor, a second gassupply pipe configured to supply a reactive gas from the gas supply unitto the reactor, a first bypass pipe branched off from the first gassupply pipe and connected to an exhaust unit, and a second bypass pipebranched off from the second gas supply pipe and connected to theexhaust unit.

In particular, the gas supply unit may include the source gas supplyunit 16, a purge gas supply unit 17, and a reactive gas supply unit 18.The gas supply unit may include a source gas supply pipe 1 configured tosupply a source gas from the source gas supply unit 16 to the reactor10, and a source gas bypass pipe 2 branched off from the source gassupply pipe 1 and connected to an exhaust line 11. The gas supply unitmay include a reactive gas supply pipe 3 configured to supply a reactivegas from the reactive gas supply unit 18 to the reactor 10, and areactive gas bypass pipe 4 branched off from the reactive gas supplyunit 3 and connected to the exhaust line 11. The gas supply unit mayinclude a purge gas supply pipe 5 configured to supply a purge gas fromthe purge gas supply unit 17 to the reactor 10, and the purge gas supplypipe 5 may be branched off to be connected to the source gas supply pipe1 and the reactive gas supply pipe 3 respectively.

The gas supply unit may further include at least one mass flowcontroller (MFC) configured to control flow rate(s) of the source gasand/or the reactive gas and/or the purge gas. MFCs may be digitallycontrolled MFCs.

Referring to FIG. 1, the gas supply unit may include a first MFC 7, asecond MFC 9, and a third MFC 8.

The first MFC 7 may be connected to the source gas supply unit 16 andthe source gas supply pipe 1 and may control the flow rate of the sourcegas supplied to the reactor 10 and/or the source gas bypass pipe 2. Thesecond MFC 9 may be connected to the reactive gas supply unit 18 and thereactive gas supply pipe 3 and may control the flow rate of the reactivegas supplied to the reactor 10 and/or the reactive gas bypass pipe 4.The third MFC 8 may be connected to the purge gas supply unit 17 and thepurge gas supply pipe 5 and may control the flow rate of the purge gassupplied to the reactor 10.

In addition, the gas supply unit may further include valves v1 to v7configured to control gas flow in pipes. The operations of the valves v1to v7 in each operation during a thin film forming process will bedescribed with reference to FIGS. 3A to 3D.

The first, third, and second MFCs 7, 8, and 9 and the valves v1 to v7may be controlled to select the types and amounts of the source gas andthe reactive gas that are supplied to the reactor 10.

The reactor 10 may be a space for forming a thin film on a substrate,e.g., a closed space. To this end, the space of the reactor 10 may beseparated from the outside of the reactor 10 using a sealing member suchas 0-ring and may generally be maintained at an atmospheric pressure orlower. A substrate support member or susceptor (not shown) on which asubstrate is mounted may be placed in the reactor 10, and a gate valve(not shown) that allows the substrate to enter and exit may be providedat a side surface of the reactor 10. In this case, the gate valve may beopened only when the substrate is loaded and unloaded and remain closedduring the process.

The reactor 10 may include a gas injection member 13. The gas injectionmember 13 may be configured to uniformly supply, onto a substrate, thesource gas and the reactive gas respectively supplied via the source gassupply pipe 1 and the reactive gas supply pipe 3, and the purge gassupplied via the purge gas supply pipe 5. For example, the gas injectionmember 13 may be a shower head. In another embodiment, the gas injectionmember 13 may be connected to an RF plasma generator 12, andaccordingly, a PEALD process may be performed. In another embodiment,the gas injection member 13 may act as a plasma electrode.

The exhaust unit may include a single exhaust line 11. The reactor 10 isconnected to the exhaust unit via the single exhaust line 11, and theexhaust unit is connected to the exhaust pump unit 15 via the singleexhaust line 11. Thus, the source gas and/or the reactive gas havingbeen through the reactor 10 may be discharged via the exhaust line 11and the exhaust pump unit 15.

The reactor 10, the source gas bypass pipe 2, and the reactive gasbypass pipe 4 are connected to the single exhaust line 11. Thus, a paththrough which the bypassed source gas or reactive gas is discharged isalso the exhaust line 11, which may be the same as a path through whichthe source gas or reactive gas purged from the reactor 10 is discharged.

In addition, the exhaust unit may include a roughing valve 14 configuredto control the pressure in the reactor 10.

As described above, the substrate processing apparatus 100 of FIG. 1 maybe an ALD apparatus that deposit a SiN film by PEALD. That is, thesubstrate processing apparatus 100 may repeat a source gas supplyoperation, a source gas purge operation, a reactive gas supplyoperation, a plasma supply operation, and a reactive gas purgeoperation. In this case, DCS and NH₃ are alternately supplied to thereactor 10 to perform an ALD process, and when DCS is supplied to thereactor 10, NH₃ may be discharged to the exhaust pump unit 15 via thereactive gas bypass pipe 4, and when NH₃ is supplied to the reactor 10,DCS may be discharged to the exhaust pump unit 15 via the source gasbypass pipe 2. That is, the source/reactive gases may be alternatelysupplied to the reactor 10 and the corresponding bypass pipe in aswitching manner, thereby maintaining a continuous flow state, andaccordingly, pressure fluctuation in the gas supply pipe and the reactor10 may be reduced, resulting in maintaining processing stability. Tominimize a pressure fluctuation during a thin film forming process, gaspressure in a gas supply line is kept constant. To this end, forexample, the same amount of source gas as that of source gas supplied tothe reactor 10 via the source gas supply pipe 1 during the source gassupply operation may be supplied to the exhaust unit via the source gasbypass pipe 2 during operations other than the source gas supplyoperation.

FIG. 2 is a schematic diagram illustrating a thin film forming methodaccording to embodiments of the present disclosure.

Referring to FIG. 2, the thin film forming method may include a firstoperation of supplying a source gas into a reactor (operation 201), asecond operation of purging the source gas in the reactor (operation202), a third operation of supplying a reactive gas into the reactor(operation 203), a fourth operation of supplying plasma (operation 204),and a fifth operation of purging the reactive gas in the reactor(operation 205). The source gas supply, the reactive gas supply, and theplasma supply may be sequentially performed. In addition, a cycle of thefirst operation (operation 201) to the fifth operation (operation 205)may be repeated several times until a thin film having a desiredthickness is formed.

During the first to fifth operations (operations 201 to 205), the purgegas may be continuously supplied to a reaction space. The purge gasrenders a pressure in the reaction space uniform, and may purge thesource gas and the reactive gas from the reactor in the second and fifthoperations (operations 202 and 205). During the second operation(operation 202), the source gas and the purge gas in the reactor may bedischarged via an exhaust line of an exhaust unit. In addition, duringthe fifth operation (operation 205), the reactive gas and the purge gasin the reactor may be discharged via the exhaust line of the exhaustunit.

Meanwhile, when one of the source gas and the reactive gas is suppliedto the reactor via a source gas supply pipe or a reactive gas supplypipe, the other gas may be bypassed to the exhaust unit via a source gasbypass pipe or a reactive gas bypass pipe. In addition, when one of thesource gas and the reactive gas is purged from the reactor to theexhaust unit, the source gas and the reactive gas may be bypassed to theexhaust unit via the source gas bypass pipe and the reactive gas bypasspipe, respectively.

In particular, in the first operation (operation 201), while the sourcegas is supplied to the reactor, the reactive gas may be bypassed to theexhaust unit via the reactive gas bypass pipe. In the second operation(operation 202), while the source gas is purged from the reactor to theexhaust unit, the source gas and the reactive gas may be bypassed to theexhaust unit via the source gas bypass pipe and the reactive gas bypasspipe, respectively. In the third and fourth operations (operations 203and 204), while the reactive gas is supplied to the reactor, the sourcegas may be bypassed to the exhaust unit via the source gas bypass pipe.In the fifth operation (operation 205), while the reactive gas is purgedfrom the reactor to the exhaust unit, the source gas and the reactivegas may be bypassed to the exhaust unit via the source gas bypass pipeand the reactive gas bypass pipe, respectively. Gas discharge throughthese bypass pipes is intended to maintain a continuous flow state ofgases, and accordingly, a pressure in the gas supply pipes and thereactor may be kept constant.

As described above, to minimize pressure fluctuation by maintaining gaspressure constant, the same amount of source gas as that of source gassupplied during the source gas supply operation may be supplied to theexhaust unit during operations other than the source gas supplyoperation. Similarly, the same amount of reactive gas as that ofreactive gas supplied during the reactive gas supply operation may besupplied to the exhaust unit during operations other than the reactivegas supply operation.

That is, as illustrated in FIG. 2, while the same amount of source gasis supplied to the reactor via the source gas supply pipe during thefirst operation (operation 201) and is supplied to the exhaust unit viathe source gas bypass pipe during the second to the fifth operations(operations 202 to 205), the same amount of reactive gas is supplied tothe reactor via the reactive gas supply pipe during the third and fourthoperations (operations 203 and 204) and is supplied to the exhaust unitvia the reactive gas bypass pipe during the first, second, and fifthoperations (operations 201, 202, and 205). As such, supply flow rates ofthe source gas and the reactive gas remain constant during a thin filmforming process, and only directions in which the source gas and thereactive gas are supplied may be changed. That is, the gas supply unit,particularly an MFC, may continuously supply the same amount(s) of thesource gas and/or the reactive gas. Accordingly, much greater amounts ofthe source gas and the reactive gas than required in the reaction may bewasted.

As described above, a path through which the bypassed gas is dischargedis the same as a path through which a gas discharged from the reactor isdischarged. For example, in the second operation (operation 202), thesource gas may be discharged from the reactor, and the reactive gas maybe bypassed via the reactive gas bypass pipe. In this regard, the paththrough which the source gas is discharged from the reactor and the paththrough which the bypassed reactive gas is discharged may be the same,i.e., the exhaust line 11 (see FIG. 1). In this case, the source gas andthe reactive gas that have been introduced into the exhaust line 11 mayreact with each other to thereby generate by-products. These by-productsmay adversely affect the performance of an exhaust line, an exhaustpump, and a scrubber. This will be described in more detail withreference to FIGS. 3A to 3D.

FIGS. 3A to 3D are schematic diagrams illustrating the substrateprocessing apparatus 100 of FIG. 1 performing the thin film formingmethod of FIG. 2.

Referring to FIGS. 2 and 3A, the first operation of supplying a sourcegas into the reactor 10 (operation 201) is performed. During the firstoperation (operation 201), the source gas is supplied to the reactor 10via the source gas supply unit 16, the first MFC 7, and the source gassupply pipe 1, and a reactive gas is bypassed to an exhaust unit via thereactive gas supply unit 18, the second MFC 9, and the reactive gasbypass pipe 4. To this end, a source gas supply valve v1 and a reactivegas bypass valve v4 may be opened, and a source gas bypass valve v2 anda reactive gas supply valve v3 may be closed. During this operation,purge gas supply valves v5, v6, and v7 may be opened, and a purge gasmay be continuously supplied into a reaction space such that a pressurein the reaction space is rendered constant.

Referring to FIGS. 2 and 3B, the second operation of purging the sourcegas in the reactor 10 to the exhaust unit via the exhaust line 11(operation 202) is performed. During the second operation (operation202), the source gas is bypassed to the exhaust unit via the source gassupply unit 16, the first MFC 7, and the source gas bypass pipe 2, andthe reactive gas is bypassed to the exhaust unit via the reactive gassupply unit 18, the second MFC 9, and the reactive gas bypass pipe 4. Tothis end, the source gas supply valve v1 and the reactive gas supplyvalve v3 may be closed, and the source gas bypass valve v2 and thereactive gas bypass valve v4 may be open. During this operation, thepurge gas supply valves v5, v6, and v7 remain open and the purge gas iscontinuously supplied into the reaction space, thereby purging thesource gas in the reactor 10.

During this operation (operation 202), the source gas purged from thereactor 10, the source gas bypassed via the source gas bypass pipe 2,and the reactive gas bypassed via the reactive gas bypass pipe 4 may beintroduced into the exhaust line 11. As described above, the flow rateof the source gas supplied during the source gas supply operation is thesame as that of the source gas supplied during the source gas purgeoperation. That is, the source gas is bypassed, at the same flow rate asthat of source gas supplied to the reactor 10, to the exhaust unit viathe source gas bypass pipe 2 in the source gas purge operation. Forexample, 2,000 sccm of DSC is supplied to both the reactor 10 and theexhaust unit. Also, the flow rate of the reactive gas supplied to thereactor 10 is the same as that of reactive gas bypassed to the exhaustunit. As such, when a large amount of the source gas and a large amountof the reactive gas are simultaneously introduced into the exhaust line11, the source gas and the reactive gas may react with each other in theexhaust line 11 to thereby generate reaction by-products, and thesereaction by-products may remain as solids in the exhaust line 11. Theseresidual solids deteriorate equipment performance and reduce apreventive maintenance (PM) cycle of equipment, thus reducing actualoperation time.

Referring to FIGS. 2 and 3C, the third operation of supplying a reactivegas into the reactor 10 (operation 203) and the fourth operation ofsupplying plasma (operation 204) are performed. During the third andfourth operations (operations 203 and 204), the reactive gas is suppliedto the reactor 10 via the reactive gas supply unit 18, the second MFC 9,and the reactive gas supply pipe 3, and the source gas is bypassed tothe exhaust unit via the source gas supply unit 16, the first MFC 7, andthe source gas bypass pipe 2. To this end, the reactive gas supply valvev3 and the source gas bypass valve v2 may be open, and the reactive gasbypass valve v4 and the source gas supply valve v1 may be closed. Duringthis operation, the purge gas supply valves v5, v6, and v7 may be open,and the purge gas may be continuously supplied into a reaction spacesuch that a pressure in the reaction space is rendered constant.

Referring to FIGS. 2 and 3D, the fifth operation of purging the reactivegas in the reactor 10 to the exhaust unit via the exhaust line 11(operation 205) is performed. During the fifth operation (operation205), the source gas is bypassed to the exhaust unit via the source gassupply unit 16, the first MFC 7, and the source gas bypass pipe 2, andthe reactive gas is bypassed to the exhaust unit via the reactive gassupply unit 18, the second MFC 9, and the reactive gas bypass pipe 4. Tothis end, the source gas supply valve v1 and the reactive gas supplyvalve v3 may be closed, and the source gas bypass valve v2 and thereactive gas bypass valve v4 may be open. During this operation, thepurge gas supply valves v5, v6, and v7 remain open and the purge gas iscontinuously supplied into the reaction space, thereby purging thereactive gas in the reactor 10.

During this operation (operation 205), the reactive gas purged from thereactor 10, the source gas bypassed via the source gas bypass pipe 2,and the reactive gas bypassed via the reactive gas bypass pipe 4 may beintroduced into the exhaust line 11. As described above, the flow rateof the reactive gas supplied during the reactive gas supply operation isthe same as that of the reactive gas supplied during the reactive gaspurge operation. That is, the reactive gas is bypassed at the same flowrate as that of the reactive gas supplied to the reactor 10 to theexhaust unit via the reactive gas bypass pipe 2 in the reactive gaspurge operation. Also, the flow rate of the source gas supplied to thereactor 10 is the same as that source gas bypassed to the exhaust unit.When a large amount of the source gas and a large amount of the reactivegas are simultaneously introduced into the exhaust line 11, the sourcegas and the reactive gas may react with each other in the exhaust line11 to thereby generate reaction by-products, and these reactionby-products may remain as solids in the exhaust line 11. These residualsolids deteriorate equipment performance and reduce a PM cycle ofequipment, thus reducing actual operation time.

FIG. 4 is a schematic diagram illustrating a thin film forming methodaccording to other embodiments of the present disclosure. The thin filmforming method of FIG. 4 is a method of addressing the aforementionedproblems in that the generated reaction byproducts deteriorate theperformance of an exhaust line, an exhaust pump, and a scrubber andreduce the PM cycle, and large amounts of the source gas and thereactive gas are wasted. Hereinafter, detailed descriptions of the sameelements as those in the previous embodiments will be omitted.

Referring to FIG. 4, the thin film forming method may include a firstoperation of supplying a source gas into a reactor (operation 401), asecond operation of purging the source gas in the reactor (operation402), a third operation of supplying a reactive gas into the reactor(operation 403), a fourth operation of supplying plasma (operation 404),and a fifth operation of purging the reactive gas in the reactor(operation 405). The source gas supply, the reactive gas supply, and theplasma supply may be sequentially performed. During the source gassupply, the reactive gas supply, and the plasma supply, a purge gas mayalso be continuously supplied into a reaction space. In addition, acycle of the first operation (401) to the fifth operation (405) may berepeated several times until a thin film having a desired thickness isformed.

Unlike in FIG. 2, according to the thin film forming method of FIG. 4, agas supply unit supplies a source gas to a reactor in the firstoperation of supplying a source gas (operation 401), and in the otheroperations (operations 402 to 405), the gas supply unit may stop thesupply of the source gas and thus not supply the source gas to a sourcegas bypass pipe or significantly reduce a flow rate of the source gassupplied to the source gas bypass pipe. Similarly, the gas supply unitsupplies a reactive gas to the reactor in the third operation ofsupplying a reactive gas (operation 403) and the fourth operation(operation 404), and in the other operations (operations 401, 402, and405), the gas supply unit may stop the supply of the reactive gas andthus not supply the reactive gas to a reactive gas bypass pipe orsignificantly reduce a flow rate of the reactive gas supplied to thereactive gas bypass pipe. However, to completely stop the supply of thesource gas and/or the reactive gas, i.e., to adjust a supply amount ofthe source gas and/or the reactive gas to 0, a valve (particularly, avalve placed inside an MFC) has to be closed, which is inconvenient, andwhen the valve is reopened after being completely closed, a change inpressure inside a gas pipe may occur due to a flow rate change.Therefore, the flow rates of source gas and reactive gas bypassed may bereduced rather than being adjusted to 0. Accordingly, a dramatic changein pressure that may occur when a gas flow rate is changed may beminimized. In particular, a gas supply unit, particularly an MFC maycontinuously supply the source gas and the reactive gas during the firstto fifth operations, but the flow rates thereof may be controlled. Forexample, the gas supply unit supplies the source gas at a first flowrate R1 during the first operation (operation 401), while supplying thesource gas at a third flow rate R3 that is less than the first flow rateR1 during the second to fifth operations (operations 402 to 405). Forexample, the third flow rate R3 may be greater than 0 and less than thefirst flow rate R1. For example, the third flow rate R3 may be in arange of about ⅛ to about 1/10 of the first flow rate R1. Similarly, thegas supply unit supplies a reactive gas at a second flow rate R2 duringthe third and fourth operations (operations 403 and 404), whilesupplying the reactive gas at a fourth flow rate R4 that is less thanthe second flow rate R2 during the second and fifth operations(operation 402 and 405). For example, the fourth flow rate R4 may begreater than 0 and less than the second flow rate R2. The fourth flowrate R4 may be in a range of about ⅛ to about 1/10 of the second flowrate R2.

In a further embodiment, the thin film forming method may furtherinclude a source gas pre-flow operation of supplying the source gas atthe first flow rate R1 during a first predetermined period t_(spf)(operation 406) before the first operation. By flowing at the same flowrate, i.e., the first flow rate R1 of the source gas to a bypass lineright before the source gas is supplied to the reactor at the first flowrate R1, a change in gas pressure in a source gas supply pipe may beminimized such that the thin forming process is maintained stable. Thesource gas pre-flow operation (operation 406) may be started during anyone of the second to fifth operations (operations 402 to 405) accordingto the first predetermined period t_(spf). For example, the source gaspre-flow operation (operation 406) may be started during the fifthoperation (operation 405) as illustrated in FIG. 4, or may be startedduring the fourth operation (operation 404) as illustrated in FIG. 5.For example, a total processing time (t2+t3+t4+t5) of the second tofifth operations (operations 402 to 405) may be 1.5 seconds, and thefirst predetermined period t_(spf) may be 1.3 seconds or less.

However, as illustrated in FIG. 5, when the source gas pre-flowoperation (operation 406) is started during operation 404, or when thesource gas pre-flow operation (operation 406) is started during any oneof the second to fifth operations (operations 402 to 405), a largeamount of the reactive gas from the reactor and a large amount (in thiscase, the first flow rate R1) of the source gas from the source gasbypass pipe may be simultaneously introduced to the exhaust path 11during the fifth operation (operation 405), thereby generating a largeamount of reaction by-products. In addition, the source gas may bewasted during the source gas pre-flow operation (operation 406).Therefore, the source gas pre-flow operation (operation 406) may bestarted during the fifth operation (operation 405). That is, the firstpredetermined period t_(spf) may be less than a processing time t5 ofthe fifth operation.

Referring back to FIG. 4, similar to the source gas pre-flow operation(operation 406), the thin film forming method may further include,before the third operation, a reactive gas pre-flow operation (operation407) of supplying a reactive gas at the second flow rate R2 during asecond predetermined period t_(rpf). The second predetermined periodt_(rpf) may be less than a processing time t2 of the second operation.

During the second operation (operation 402) of FIG. 4, the flow rate ofthe source gas bypassed to the exhaust unit may be gradually reducedfrom the first flow rate R1 to the third flow rate R3. During the fifthoperation (operation 405) of FIG. 4, the flow rate of the source gasbypassed to the exhaust unit may be gradually increased from the thirdflow rate R3 to the first flow rate R1. The gradual decrease or increasein the flow rate of the source gas flowing in the bypass pipe in thesecond operation (operation 402) and the fifth operation (operation 405)is due to the fact that the amount of the source gas in the bypass pipeis slowly increased or decreased due to the physical length of thebypass pipe. Similarly, the flow rate of the reactive gas bypassed tothe exhaust unit may be gradually increased from the fourth flow rate R4to the second flow rate R2 during the second operation (operation 402),and the flow rate of the reactive gas bypassed to the exhaust unit maybe gradually reduced from the second flow rate R2 to the fourth flowrate R4 during the fifth operation (operation 405).

Accordingly, to minimize reaction by-products generated in the exhaustline, as illustrated in FIG. 6, the source gas pre-flow operation(operation 406) may be started after the flow rate of the reactive gasbypassed to the exhaust unit is reduced from the second flow rate R2 tothe fourth flow rate R4 during the fifth operation (operation 405). Thatis, after a time t_(i) at which the flow rate of the reactive gasbypassed to the exhaust unit is reduced from the second flow rate R2 tothe fourth flow rate R4, the source gas pre-flow operation (operation406) may be started at a time t_(j).

Similarly, to minimize reaction by-products generated in the exhaustline, as illustrated in FIG. 6, the reactive gas pre-flow operation(operation 407) may be started after the flow rate of the source gasbypassed to the exhaust unit during the second operation is reduced fromthe first flow rate R1 to the third flow rate R3 (operation 402). Thatis, after a time t_(x) at which the flow rate of the source gas bypassedto the exhaust unit is reduced from the first flow rate R1 to the thirdflow rate R3, the reactive gas pre-flow operation (operation 407) may bestarted at a time t_(y).

FIGS. 7A to 7D are schematic diagrams illustrating the substrateprocessing apparatus 100 of FIG. 1 performing the thin film formingmethod of FIG. 4. Hereinafter, detailed descriptions of the sameelements as those in the previous embodiments will be omitted.

Referring to FIGS. 4 and 7A, the first operation of supplying a sourcegas into the reactor 10 (operation 401) is performed. During the firstoperation (operation 401), the source gas may be supplied at the firstflow rate R1 into the reactor 10 via the source gas supply unit 16, thefirst MFC 7, and the source gas supply pipe 1. To supply the source gasat the first flow rate R1, the first MFC 7 may be programmed to supplythe source gas at the first flow rate R1 during the first operation(operation 401). During the first operation (operation 401), thereactive gas may be bypassed to the exhaust line 11 at the fourth flowrate R4 via the reactive gas supply unit 18, the second MFC 9, and thereactive gas bypass pipe 4. To supply the reactive gas at the fourthflow rate R4, the second MFC 9 may be programmed to supply the reactivegas at the fourth flow rate R4 during the first operation (operation401).

Referring to FIGS. 4 and 7B, the second operation of purging the sourcegas in the reactor 10 (operation 402) is performed. During the secondoperation (operation 402), the source gas may be bypassed to the exhaustunit via the source gas supply unit 16, the first MFC 7, and the sourcegas bypass pipe 2 at the third flow rate R3 that is less than the firstflow rate R1. To supply the source gas at the third flow rate R3, thefirst MFC 7 may be programmed to supply the source gas at the third flowrate R3 during the second operation (operation 402). In addition, duringthe second operation (operation 402), the reactive gas may be bypassedto the exhaust unit via the reactive gas supply unit 18, the second MFC9, and the reactive gas bypass pipe 4 at the fourth flow rate R4 that isless than the second flow rate R2. To supply the reactive gas at thefourth flow rate R4, the second MFC 9 may be programmed to supply thereactive gas at the fourth flow rate R4 during the second operation(operation 402). In a further embodiment, as described above, thereactive gas pre-flow operation (operation 407) may be performed. Toperform the reactive gas pre-flow operation (operation 407), the secondMFC 9 may be programmed to supply the reactive gas at the second flowrate R2 during the second predetermined period t_(rpf) before the thirdoperation (operation 403).

During the second operation (operation 402), the source gas purged fromthe reactor 10, the source gas bypassed via the source gas bypass pipe 2at the third flow rate R3, and the reactive gas bypassed via thereactive gas bypass pipe 4 at the fourth flow rate R4 may be introducedinto the exhaust line 11. Accordingly, as the flow rate of the bypassedreactive gas decreases, i.e., as the fourth flow rate R4 decreases, theamounts of the source gas and the reactive gas reacted in the exhaustline 11 during the second operation (operation 402) may be reduced.

Referring to FIGS. 4 and 7C, the third operation of supplying a reactivegas into the reactor 10 (operation 403) and the fourth operation ofapplying plasma (operation 404) are performed. During the third andfourth operations (operations 403 and 404), the second flow rate R2 ofthe reactive gas may be supplied to the reactor 10 via the reactive gassupply unit 18, the second MFC 9, and the reactive gas supply pipe 3. Tosupply the second flow rate R2 of the reactive gas, the second MFC 9 maybe programmed to supply the reactive gas at the second flow rate R2during the third and fourth operations (operations 403 and 404). Inaddition, during the third and fourth operations (operations 403 and404), the third flow rate R3 of the source gas may be bypassed to theexhaust unit via the source gas supply unit 16, the first MFC 7, and thesource gas bypass pipe 2. To supply the third flow rate R3 of the sourcegas, the first MFC 7 may be programmed to supply the source gas at thethird flow rate R3 during the third and fourth operations (operations403 and 404).

Referring to FIGS. 4 and 7D, the fifth operation of purging the reactivegas in the reactor 10 (operation 405) is performed. During the fifthoperation (operation 405), the fourth flow rate R4 of the reactive gasmay be bypassed to the exhaust unit via the reactive gas supply unit 18,the second MFC 9, and the reactive gas bypass pipe 4. To supply thefourth flow rate R4 of the reactive gas, the second MFC 9 may beprogrammed to supply the reactive gas at the fourth flow rate R4 duringthe fifth operation (operation 405). In addition, during the fifthoperation (operation 405), the third flow rate R3 of the source gas maybe bypassed to the exhaust unit via the source gas supply unit 16, thefirst MFC 7, and the source gas bypass pipe 2. To supply the third flowrate R3 of the source gas, the first MFC 7 may be programmed to supplythe source gas at the third flow rate R3 during the fifth operation(operation 405). In a further embodiment, as described above, the sourcegas pre-flow operation (operation 406) may be performed. To perform thesource gas pre-flow operation (operation 406), the first MFC 7 may beprogrammed to supply the reactive gas at the first flow rate R1 duringthe first predetermined period t_(spf) before the first operation(operation 401).

During the fifth operation (operation 405), the reactive gas purged fromthe reactor 10, the third flow rate R3 of the source gas bypassed viathe source gas bypass pipe 2, and the fourth flow rate R4 of thereactive gas bypassed via the reactive gas bypass pipe 4 may beintroduced into the exhaust line 11. Accordingly, as the flow rate ofthe bypassed source gas decreases, i.e., as the third flow rate R3decreases, the amounts of the source gas and the reactive gas reacted inthe exhaust line 11 during the fifth operation (operation 405) may bereduced.

As described above, the first, third, and second MFCs 7, 8, and 9 may bedigitally controlled MFCs. Accordingly, the substrate processingapparatus according to the present disclosure may adjust the flow ratesof a source gas and a reactive gas in each operation of the thin filmforming process by appropriately programming MFCs without controllingvalves.

A method of controlling the flow rates of gases by using the MFCs of thesubstrate processing apparatus 100 of FIG. 7 to perform the thin filmforming process of FIG. 4 will be described in detail as follows:

1) The first flow rate R1, the third flow rate R3 that is less than thefirst flow rate R1, and the respective processing time periods t₁ to t₅of the first to fifth operations may be input to the first MFC 7. Thefirst MFC 7 may be programmed to adjust the amount of the source gas tocorrespond to each time period based on the input first flow rate R1,the input third flow rate R3, and the input respective processing timeperiods t₁ to t₅ of the first to fifth operations.

In particular, the first MFC 7 may be programmed to supply the sourcegas at the first flow rate R1 during the first operation (operation 401)and supply the source gas at the third flow rate R3 during the second tofifth operations (operations 402 to 405).

2) In a further embodiment, to minimize a gas pressure fluctuation inthe source gas supply pipe, the first MFC 7 may flow the same flow rate,i.e., the first flow rate R1 of the source gas to the bypass line rightbefore supplying the source gas at the first flow rate R1 to thereactor. To this end, the first MFC 7 may be programmed to supply thesource gas at the first flow rate R1 during the first operation(operation 401), supply the source gas at the third flow rate R3 afterthe first operation (operation 401), and supply the source gas at thefirst flow rate R1 during the first predetermined period t_(spf) beforethe first operation (operation 401).

3) As described above, the third flow rate R3 may be 0 or higher. Thus,the first MFC 7 may continuously supply the source gas during the firstto fifth operations (operations 401 to 405), and accordingly, a valve inthe first MFC 7 does not need to be opened and closed repeatedly.

4) The second flow rate R2, the fourth flow rate R4 that is less thanthe second flow rate R2, and the respective processing time periods t₁to t₅ of the first to fifth operations may be input to the second MFC 9.The second MFC 9 may be programmed to adjust the amount of the reactivegas to correspond to each time period based on the input second flowrate R2, the input fourth flow rate R4, and the input respectiveprocessing time periods t₁ to t₅ of the first to fifth operations.

In particular, the second MFC 9 may be programmed to supply the reactivegas at the second flow rate R2 during the third and fourth operations(operations 403 and 404) and supply the reactive gas at the fourth flowrate R4 during the first, second, and fifth operations (operations 401,402, and 405).

5) In a further embodiment, to minimize a gas pressure fluctuation inthe reactive gas supply pipe in the third operation (operation 403), thesecond MFC 9 may flow the same flow rate, i.e., the second flow rate R2of the reactive gas to the bypass line right before supplying thereactive gas at the second flow rate R2 to the reactor. To this end, thesecond MFC 9 may be programmed to supply the reactive gas at the secondflow rate R2 during the third and fourth operations (operations 403 and404), supply the reactive gas at the fourth flow rate R4 that is lessthan the second flow rate R2 after the fourth operation (operation 404),and supply the reactive gas at the second flow rate R2 during the secondpredetermined period t_(rpf) before the third operation (operation 403).

6) As described above, the fourth flow rate R4 may be 0 or higher. Thus,the second MFC 9 may continuously supply the reactive gas during thefirst to fifth operations (operations 401 to 405), and accordingly, avalve in the second MFC 9 does not need to be opened and closedrepeatedly.

7) That is, the first MFC 7 may control the flow rate of the gas in thesource gas supply pipe 1 and the source gas bypass pipe 2. Inparticular, to address the aforementioned problems, the first MFC 7 maybe configured such that the flow rate of the gas in the source gasbypass pipe 2 is less than that of the gas in the source gas supply pipe1.

Similarly, the second MFC 9 may control the flow rate of the gas in thereactive gas supply pipe 3 and the reactive gas bypass pipe 4. Inparticular, to address the aforementioned problems, the second MFC 9 maybe configured such that the flow rate of the gas in the reactive gasbypass pipe 4 is less than that of the gas in the reactive gas supplypipe 3.

8) In summary, the first MFC 7 and the second MFC 9 may be programmed torespectively decrease the flow rates of the corresponding gases when thesource gas and the reactive gas are bypassed to the exhaust line 11 andrespectively increase the flow rates of the corresponding gases when thesource gas and the reactive gas are supplied to the reactor 10.

FIG. 8 illustrates the consumption of a DCS source used via the sourcegas bypass pipe 2 during the second to fifth operations (operations 402to 405) according to the first predetermined period t_(spf) of thesource gas pre-flow operation (operation 406) when the thin film formingmethod of FIG. 4 is used, and the thickness of the resultantly depositedSiN thin film. In one embodiment, operations in which the source gas isnot supplied, i.e., the second to fifth operations (operations 402 to405), may be performed for 1.5 seconds. The thin film forming method ofFIG. 2 is the same as the case in which the first predetermined periodt_(spf) of the source gas pre-flow operation (operation 406) of FIG. 4is set to 1.5 seconds. The first predetermined period t_(spf) of 1.5seconds is set as a reference of FIG. 8, which corresponds to the caseof FIG. 2. As a result of increasing the first predetermined periodt_(spf) of the source gas pre-flow operation (operation 406) from 0.7seconds to 1.3 seconds at an interval of 0.2 seconds, the amount of thesource gas discharged via the source gas bypass pipe 2 when the firstpredetermined period t_(spf) is 0.7 seconds was reduced by about 60%compared to the amount of the source gas discharged when the firstpredetermined period t_(spf) is 1.5 seconds (i.e., Ref.). In addition,it was confirmed that the length of the first predetermined periodt_(spf) did not affect the SiN thin film deposited in the reactor 10,particularly the thickness of the SiN thin film. In particular, it isevident that, even when the first predetermined period t_(spf) is 0.7seconds, a SiN thin film having the same thickness as an existing SiNthin film (i.e., Ref.) is deposited. This is because the source gassupplied to the reactor 10 in the source gas supply operation (operation401) contributes to the formation of a SiN thin film performed on asubstrate in the reactor 10, and the source gas bypassed in the otheroperations (operations 402 to 405) does not contribute to the formationof a SiN thin film in the reactor 10 at all.

FIG. 9 illustrates uniformity of a SiN thin film according to the firstpredetermined period t_(spf) of the source gas pre-flow operation(operation 406) when the thin film forming method of FIG. 4 is used.

Similar to the experiment of FIG. 8, as a result of increasing the firstpredetermined period t_(spf) of the source gas pre-flow operation(operation 406) of FIG. 4 from 0.7 seconds to 1.3 seconds at an intervalof 0.2 seconds, it was confirmed that the SiN thin film wascomparatively uniform regardless of the length of the firstpredetermined period t_(spf) of the source gas pre-flow operation(operation 406). That is, it was confirmed that the length of the firstpredetermined period t_(spf) did not affect the SiN thin film depositedin the reactor 10, particularly the uniformity of the SiN thin film.

It was also confirmed that the uniformity of a thin film depositedaccording to the thin film forming method of FIG. 4 was better than thatof a thin film deposited according to the thin film forming method ofFIG. 2. This is because burden on and damage to an exhaust line, anexhaust pump, and a scrubber were minimized by reducing the consumptionof a source gas discharged via a bypass pipe, and a pressure fluctuationin a source gas supply pipe was minimized through the source gaspre-flow operation (operation 406).

Through the experiments of FIGS. 8 and 9, it was confirmed that a gasdischarged through a bypass pipe did not affect a thin film deposited ina reactor. It was also confirmed that by using the thin film formingprocess of FIG. 4, not only the consumption of a gas discharged viabypass pipe could be reduced, but burden on and damage to an exhaustline, an exhaust pump, and a scrubber could also be minimized, withoutaffecting a thin film deposited in a reactor, thus increasing the PMcycle of equipment and contributing to productivity enhancement.

Although an ALD process or a PEALD process has mainly been described inthe above-described embodiments, this is provided for illustrativepurposes only. It is noted that the technical spirit of the presentdisclosure may be applied to a chemical vapor deposition (CVD) processother than a PEALD process, a cleaning process, and any other processesrequiring separate discharge of a fluid.

As is apparent from the foregoing description, in a thin film formingprocess of a substrate processing apparatus, cost of ownership (CoO) ofequipment may be saved by reducing the consumption of unnecessary sourcegas and reactive gas that do not contribute to a reaction. In addition,according to one embodiment of the present disclosure, a thin filmforming process of a substrate processing apparatus including a singleexhaust line, by reducing the consumption of a gas not supplied to areactor and discharged via a bypass pipe, burden on and damage to theapparatus due to the generation of reaction by-products in an exhaustpipe may be minimized, PM cycles of an exhaust line, an exhaust pump,and a scrubber may be increased, and productivity may be enhanced.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While one or more embodiments have been described with reference to thefigures, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the disclosure as defined by thefollowing claims.

What is claimed is:
 1. A thin film forming method comprising: a firstoperation of supplying a source gas at a first flow rate into a reactorvia a first mass flow controller; a second operation of purging thesource gas in the reactor to an exhaust unit; a third operation ofsupplying a reactive gas at a second flow rate into the reactor via asecond mass flow controller; a fourth operation of supplying plasma intothe reactor; and a fifth operation of purging the reactive gas in thereactor to the exhaust unit, wherein, during the second to fifthoperations, the source gas is bypassed to the exhaust unit via the firstmass flow controller, and a flow rate of the source gas bypassed to theexhaust unit is less than the first flow rate.
 2. The thin film formingmethod of claim 1, wherein a path through which the bypassed source gasis discharged is the same as a path through which the purged source gasor reactive gas is discharged from the reactor.
 3. The thin film formingmethod of claim 1, wherein the first flow rate, a third flow rate, andrespective processing time periods of the first to fifth operations areinput to the first mass flow controller, the third flow rate being lessthan the first flow rate, and the first mass flow controller isprogrammed to adjust an amount of the source gas based on the inputfirst flow rate, the input third flow rate, and the input respectiveprocessing time periods of the first to fifth operations.
 4. The thinfilm forming method of claim 3, wherein the first mass flow controlleris programmed to: supply the source gas at the first flow rate duringthe first operation; and supply the source gas at the third flow rateduring the second to fifth operations.
 5. The thin film forming methodof claim 4, wherein a flow rate of the source gas bypassed to theexhaust unit during the second operation is gradually reduced from thefirst flow rate to the third flow rate, and the flow rate of the sourcegas bypassed to the exhaust unit during the fifth operation is graduallyincreased from the third flow rate to the first flow rate.
 6. The thinfilm forming method of claim 3, wherein the third flow rate is greaterthan 0 and less than the first flow rate.
 7. The thin film formingmethod of claim 6, wherein the third flow rate is about ⅛ to about 1/10of the first flow rate.
 8. The thin film forming method of claim 3,wherein the first mass flow controller is programmed to: supply thesource gas at the first flow rate during the first operation; supply thesource gas at the third flow rate after the first operation; and supplythe source gas at the first flow rate during a first predeterminedperiod before the first operation.
 9. The thin film forming method ofclaim 8, wherein the first predetermined period is shorter than theprocessing time of the fifth operation.
 10. The thin film forming methodof claim 8, wherein a total processing time of the second to fifthoperations is 1.5 seconds, and the first predetermined period is 1.3seconds or less.
 11. The thin film forming method of claim 8, wherein alength of the first predetermined period does not affect properties of athin film deposited in the reactor.
 12. The thin film forming method ofclaim 11, wherein the length of the first predetermined period does notaffect a thickness and uniformity of the thin film deposited in thereactor.
 13. The thin film forming method of claim 1, wherein the firstmass flow controller continuously transfers the source gas during thefirst to fifth operations.
 14. The thin film forming method of claim 1,wherein the reactive gas is bypassed to the exhaust unit via the secondmass flow controller during the first operation, the second operation,and the fifth operation, the second flow rate, a fourth flow rate, andrespective processing time periods of the first to fifth operations areinput to the second mass flow controller, the fourth flow rate beingless than the second flow rate, and the second mass flow controller isprogrammed to, based on the input second flow rate, the input fourthflow rate, and the input respective processing time periods of the firstto fifth operations: supply the reactive gas at the second flow rateduring the third and fourth operations; and supply the reactive gas atthe fourth flow rate during the first, second, and fifth operations. 15.The thin film forming method of claim 14, wherein a path through whichthe bypassed source gas or reactive gas is discharged is the same as apath through which the purged source gas or reactive gas is dischargedfrom the reactor, as the fourth flow rate decreases, amounts of thesource gas and the reactive gas reacted in the discharge path during thesecond operation are reduced, and as the third flow rate decreases, theamounts of the source gas and the reactive gas reacted in the dischargepath during the fifth operation are reduced.
 16. The thin film formingmethod of claim 5, wherein the reactive gas is bypassed to the exhaustunit via the second mass flow controller during the first, second, andfifth operations, the second mass flow controller is programmed to:supply the reactive gas at a second flow rate during the third andfourth operations; supply the reactive gas at a fourth flow rate afterthe fourth operation, the fourth flow rate being less than the secondflow rate; and supply the reactive gas at the second flow rate during asecond predetermined period before the third operation, and the secondpredetermined period is started after the flow rate of the source gasbypassed to the exhaust unit during the second operation is reduced tothe third flow rate.
 17. A substrate processing apparatus for performinga thin film forming process, the substrate processing apparatuscomprising: a gas supply unit; a reactor; an exhaust unit comprising asingle exhaust line and connected to the reactor via the single exhaustline; and an exhaust pump unit connected to the exhaust unit via thesingle exhaust line, wherein the gas supply unit comprises: a first gassupply pipe through which a source gas is supplied from the gas supplyunit to the reactor; a second gas supply pipe through which a reactivegas is supplied from the gas supply unit to the reactor; a first bypasspipe branched off from the first gas supply pipe and connected to theexhaust unit; and a second bypass pipe branched off from the second gassupply pipe and connected to the exhaust unit, wherein, when one of thesource gas and the reactive gas is supplied to the reactor via the firstgas supply pipe or the second gas supply pipe, the gas supply unit isconfigured to bypass the other gas to the exhaust unit via the firstbypass pipe or the second bypass pipe, and when one of the source gasand the reactive gas is purged from the reactor to the exhaust unit, thegas supply unit is configured to bypass the source gas and the reactivegas via the first bypass pipe and the second bypass pipe, respectively.18. The substrate processing apparatus of claim 17, wherein the gassupply unit further comprises at least one mass flow controller, whereinthe at least one mass flow controller is programmed to reduce a flowrate of the corresponding gas when the source gas or the reactive gas isbypassed to the exhaust unit.
 19. A substrate processing apparatus forperforming a thin film forming process, wherein the thin film formingprocess comprises: a first operation of supplying a source gas; a secondoperation of purging the source gas; a third operation of supplying areactive gas; a fourth operation of applying plasma; and a fifthoperation of purging the reactive gas, and the substrate processingapparatus comprises: a gas supply unit; a reactor; an exhaust unitcomprising a single exhaust line and connected to the reactor via thesingle exhaust line; and an exhaust pump unit connected to the exhaustunit via the single exhaust line, wherein the gas supply unit comprises:a first gas supply pipe through which a source gas is supplied from thegas supply unit to the reactor; a second gas supply pipe through which areactive gas is supplied from the gas supply unit to the reactor; afirst bypass pipe branched off from the first gas supply pipe andconnected to the exhaust unit; and a second bypass pipe branched offfrom the second gas supply pipe and connected to the exhaust unit, andthe gas supply unit is configured to: supply the source gas to thereactor via the first gas supply pipe during the first operation; supplythe source gas to the exhaust unit via the first bypass pipe during thesecond to fifth operations; supply the reactive gas to the reactor viathe second gas supply pipe during the third and fourth operations; andsupply the reactive gas to the exhaust unit via the second bypass pipeduring the first, second, and fifth operations.
 20. The substrateprocessing apparatus of claim 19, wherein the gas supply unit furthercomprises a first mass flow controller and a second mass flowcontroller, wherein the first mass flow controller is configured tocontrol a flow rate of a gas in the first gas supply pipe and the firstbypass pipe such that the flow rate in the first bypass pipe is lessthan the flow rate in the first gas supply pipe, and the second massflow controller is configured to control a flow rate of a gas in thesecond gas supply pipe and the second bypass pipe such that the flowrate in the second bypass pipe is less than the flow rate in the secondgas supply pipe.